1. Field of Invention
The present invention relates to a transistor. More particularly, the present invention relates to a structure of magnetic transistor.
2. Description of Related Art
The Giant Magnetoresistance Effect (GMR) is a quantum mechanical effect observed in structures with alternating thin magnetic and thin nonmagnetic sections. The GMR effect shows a significant change in electrical resistance from the zero-field high resistance state to the high-field low resistance state according to an applied external field.
FIG. 1 is a structure diagram depicting a conventional magnetic transistor 100 of the prior art. The conductive section 106 is disposed on the second magnetic section 104, and the first magnetic section 102 is disposed on the conductive section 106. The first metal 108 is adjacent to and completely covers one side of the first magnetic section 102, the conductive section 106, and the second magnetic section 104. The second metal 110 is adjacent to and completely covers the other side of the first magnetic section 102, the conductive section 106, and the second magnetic section 104.
Operation of the conventional 2-terminal magnetic transistor 100 is explained as follows. The operation of the magnetic transistor 100, for example, is according to an external applied field (for example, using the third metal 112 and the fourth metal 114 to control the direction of the dipoles of the first magnetic section 102 and the second magnetic section 104). When the conventional 2-terminal magnetic transistor 100 is turned on, a current is generated and flows in the direction of the first metal and the second metal. The current may avoid crossing any magnetic boundary (for example, a boundary between the first magnetic section 102 and the conductive section 106, or a boundary between the conductive section 106 and the second magnetic section 104, or both boundaries), and only a small percentage of the current actually passes through both boundaries resulting in only a few percent resistance changed which means a smaller GMR effect. Further, the conventional 2-terminal magnetic transistor 100 has only two output terminals, the current can only either be outputted from the first metal 108 or the second metal 110.
For the foregoing reasons, there is a need to have a magnetic transistor possess the larger GMR effect with a multi-terminal outputted capability.